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How We Rebuilt a Purified Water Validation Strategy Using Risk-Based Qualification

A South American pharmaceutical manufacturer asked Zamann Pharma Support to help validate a new Purified Water (PW) system. On paper, the project looked sound: solid equipment and a qualified vendor.

However, the failure was strategic, not technical: no solid risk assessment supported the PW validation. Instead, the team had adopted parameters without justification and never truly challenged “worst-case conditions.” As a result, the system was validated on paper, not in reality.

This reflects a recurring global issue: companies validate equipment, not risk. Consequently, they face rework, inspection findings, delays, and budget overruns.

In this case, our team reviewed the validation, traced the failure to a weak risk assessment, and identified the gaps behind it.

Challenges Faced

A detailed GAP analysis in Quality Management Systems is essential for identifying process deficiencies effectively.
  • Unjustified Critical Parameters: The team chose critical parameters without any documented rationale.
  • No Rationale for Microbial Limits or TOC Values: Likewise, nothing justified the microbial limits or Total Organic Carbon (TOC) values.
  • No Flow Velocity Rationale: Nor did the team justify flow velocity, such as a 1 m/s minimum to prevent biofilm.
  • Untested Worst-Case Conditions: Moreover, nobody truly challenged the system under worst-case conditions.
  • No Lifecycle Strategy: Finally, the client had qualification documents only, with no lifecycle strategy.
  • A Mismatch With Regulatory Expectations: Together, these gaps fell short of what regulators expect:

Zamann Pharma Support’s Approach

  • Define a Risk-Based Validation Strategy (RBVS): First, let risk drive every validation decision.
  • Create End-to-End Traceability: Next, link URS → Risk Assessment → Test Plan → PQ, so the risk assessment and PQ stay aligned.
  • Challenge Worst-Case Conditions: Then, test the system under real worst-case conditions.
  • Document Rationales Before Validation Begins: In addition, record every rationale before equipment validation begins.
  • Schedule Risk-Based Periodic Reviews: Finally, include risk re-evaluation in periodic reviews to support the ICH Q9 lifecycle approach.

Results Achieved

  • Root Cause Identified: Zamann Pharma Support traced the problem to strategy, not technology, since the equipment and vendor were sound.
  • Critical Gaps Exposed: The review exposed unjustified parameters, missing rationales for microbial limits, TOC and flow velocity, and inadequate worst-case testing. A missing lifecycle strategy further threatened long-term compliance.
  • Major System Re-Assessment: Consequently, the system needed a major re-assessment, which delayed validation by months and raised costs.
  • A Clear Lesson for Leadership: Ultimately, validation is a decision-making framework, not a document. When risk is poorly defined, it becomes a formality, not protection.
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GMP qualification and lifecycle validation activities including IQ, OQ, and PQ supporting inspection readiness in pharmaceutical manufacturing.
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Qualification and Validation for GMP Systems

Our team supports the planning, execution, and maintenance of qualification and validation activities, including IQ, OQ, and PQ, to keep GMP-regulated systems compliant and under control.

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FAQ

1. How should microbial limits and TOC acceptance criteria be justified during Purified Water validation?

Purified Water (PW) acceptance criteria should reflect applicable pharmacopoeial requirements, the water’s intended use, and a documented quality risk assessment. TOC limits must comply with the applicable pharmacopoeial monograph, while microbial alert and action levels should consider contamination risks and system performance data. For new systems, provisional monitoring limits can be established and refined as qualification data become available. Following WHO TRS 1033, Annex 3, manufacturers should use monitoring trends to demonstrate ongoing chemical and microbiological control.

 

2. Is a minimum flow velocity of 1 m/s mandatory for GMP Purified Water distribution systems?

No. A flow velocity of 1 m/s is a commonly used engineering target, not a universal GMP requirement. The appropriate velocity depends on pipe diameter, system design, operating conditions, and microbial contamination risks. WHO TRS 1033 recommends maintaining turbulent circulation, using a Reynolds number above 4,000 as an example. Manufacturers should document their hydraulic design rationale and verify flow performance during qualification, particularly under minimum-demand conditions where stagnation and biofilm risks may increase.

3. What worst-case conditions must be challenged during PW performance qualification (PQ)?

PW performance qualification should demonstrate that the system consistently delivers water meeting specifications under scientifically justified worst-case operating conditions. These may include peak consumption, minimum recirculation flow, extended periods of low demand, sanitization challenges, and sampling at microbiologically vulnerable points of use. The testing strategy must follow a documented risk assessment rather than relying solely on vendor protocols. WHO TRS 1033 also describes a three-phase validation approach covering at least 12 months to evaluate performance across seasonal variations, supported by ongoing monitoring and periodic system reviews.